In my prior applications, op. cit., I describe using a portable NMR instrument so that flow properties of rock samples can be accurately and swiftly measured, especially at remote field sites. The described principle of operation:spin-lattice relaxation times of fluids in chip samples can be accurately correlated to estimate flow properties of different rock samples. However, in a limited number of occasions related exclusively to testing of carbonate samples in the field, problems have arisen. (In this specification, the term "carbonate" includes limestones and dolostones; the former also relates to those types found to be formed by conventional chemical deposition including biological processes, as well as those limestones recipitated inorganically.)
While many other researchers have performed spin echo measurements as well as described in detail the effects of such measurements in relation to bounded media (See "SPIN ECHO OF SPINS DIFFUSING IN A BOUNDED MEDIUM," C. H. NEUMAN, PHYS. REV., Vol. 60, No. 11, June 1, 1974), none, as far as I am aware, have dealt with spin echo measurements in the context of entrained liquids diffusing in pores of carbonates, especially at on-site measurements of such samples; or have described results tying spin echo response, under these or similar types of circumstances, to permeability estimates of the samples.